Method of making gauges and other articles



W. E. HOKE METHOD OF MAKING vGAUGrES AND OIHER ARTICLES Filed July 8,1919 ml; EP- f1 mf J-lj d .1 [lmlalf 3 atented ar.. il, I9.

NITED STATES PATENT oFFlcr..

WILLIAM E. HOKE, 0F ST. LOUIS, MISSOURI, ASSIGNOB. T0 PRATTA& WHITNEYCOI- PANY, 0F NEW YORK, N. Y., A. CORPORATION 0F NEW JERSEY.

METHOD or if 3:. ING GAUGE AND OTHER ARTICLES.

To all 'whom t may concern:

Be it known that I, WILLIAM E. HOKE, a citizen of the United States,residing at St. Louis, Missouri, have invented certain new and usefulImprovements in Methods of Making Gauges and OtherArticles, lof whichthe following is a specification.

This invention' relates to a method of lapping gauge blocks or similararticles to produce identical sizes and particularly to produce v'planeparallel op osite surfaces. separated" from-each other y an assigneddimension with a high degree of accuracy. The method is in some respectssimilar to the method set forth in my copending applications for methodof making identical articles, Serial No. 252,073, filed Aug. 30th, 1918,and for method of and machine for making gauges and other articles,Serial No. 289,591, filed April 12th, 1919.

In accordance with the present invention, I effect the lapping of theopposite end surfaces of the blocks successively instead ofsimultaneously as was set forth in my aforesaid a plication. OrdinarilyVthe simultaneous apping is preferable, as it is more rapid andisusually productive of more accurate results. However, for certainclasses of work, particularly when the highest degree of accuracy is notrequired, it may be desirable to lap the surfaces successively.

In the accompanying drawing I have illustrated in' diagrammatic form amachine for practicing the method. I have also presented furtherdiagrams by which the method will be explained. It will be understoodthat the drawing is for illustrative purposes only and is not to beconstrued as defining or limiting the scope of the invention, the claimsappended to this specification being relied upon for that purpose.

.Of the drawing:

Fig. 1 is a vertical sectional view of a machine adapted forearryingvout my improved method.

Fig. 2 lis a plan view of the principal parts of the machine shown inFig. 1.

Figs. 3 to 5 are diagrammatic views further illustrating the method.

The blocks to be lapped are first formed with the desired shape and witha little more than the desired length, by any usual or preferred means.When they are to be used as gauges the blocks are hardened and otherwisesuitably treated, but these preliminary steps constitute no part of thepresent invention. After the blocks have been thus formed and treated,they are then subjected to a lapping operation or a series of lappingoperations and are otherwise acted upon, in the manner tovbe described.

Referring to Figs. 1 and 2 of the drawing, it'will be seen that Iprovide a surface plate 1 which is suitably mounted on a table or othersupport; 2. The surface plate 1 is provided with a surface 3 which ismade as nearly plane as possible `by any known( method. The severalblocks B-B to be lapped are placed-upon the surface plate and aresecured in position by cementing or otherwise. I do'not limit myself asconcerns the arrangement of the blocks, but preferably they are arrangedin a circular series as illustrated. For reducing the u per surfaces ofthe blocks B-B I provi e a lap 4 having a bottom surface 5 which is madeas nearly plane as possible. This lower surface of the lap 1s suitablyprepared and is charged with an abrasive such as line emery. Thecharacter of the lap and of the abrasive may be varied as required.`

The lap 4 rests directly on the blocks B and is entirely free to adjustitself as to parallelism with the surface plate in accordance with thelengths of the blocks. In order to effect lapping, the Vlap isv movedwith respect to the blocks, this movement preferably being in a circularpath. As illustrated, a plate 6 is secured to the la 4, this platehaving a central aperture l; in which is fitted a crank 8 on a rotatingspindle 9. It will be seen that the` entire lap is caused to partake ofthe rotative movement of the spindle. The lap is free to turn about theaxis of the crank 8 and as the result of the resistance offered by theblocks, the lap is given a rotative movement in addition tov its bodilycircular movement. The-movement of the lap 4 is continued until the lapengages all Aof the blocks equally. When this point is reached it may beassumed that the top surfaces of all the blocks are fiat orapproximately so, although the blocks may vary slightly in length.

After the blocks have been rovided with plane surfaces at one end asescribed, they are then removed from the surface plate 1 and turned overend for end so that the flat surfaces of the blocks directly engage theflat surface of the surface plate. The

blocks are now held against movementl with titi respect to the surfaceplate and this holding may be effected by wringing them into place, thiswringing action being a well known phenomenon whereby two flat surfacesstrongly adhere. lVlien two fiat surfaces are properly wrung togetheractual physical contact is very closely approximated, the

actual separation frequently being as small4 as a millionth of an inch.Then the lapping operation is re cated as before described andcontinued, pre erably until the lap again engages all oftheblocksequally.

Then the lapping movement is stopped and the lap is removed, thusleaving the blocks exposed. Certain blocks are then transferred in sucha way `as to distribute any errors or variations in the respectivelengths. It may be assumed that, with a group of blocks of slightlyvarying lengths, those at one part of the'group will average longer thanthose at another part. Following this assumption it .will be seen thatthe transferring must be such that the longer and shorter blocks will becommingled. In order that the longer and shorter blocks may be uniformlydistributed, the transferring is preferably effected symmetrically. Ifthe blocks are arranged in a circular series, it is to be expected thatthe lengths of those at one sidel will have a greater average than thelengths of those at the other side. Inasmuch as the surface plate 1 andthe lap 4 are both flat, the result is that some one or two of theblocks at one side will have a maximum length and some one or two blocksdiametrically opposite will have a. minimum length. The blocks betweenwill have lengths successively varying from the maximum to the minimum.The blocks at one side of the diametral line will have lengths greaterthan the average and those on the other side will have lengths less thanthe average. The transferring of the blocks to distribute the errors andequalize the lengths is preferably done by moving alternate blocks oralternate groups of blocks to positions diametrically opposite. Thisplaces the longer blocks between the shorter ones.

For practicing the method in the preferred manner, the number of blocksin any one circular series, such as a. to p, as shown in Fig. 3, shouldbe a multiple of four and should be at least eight. By way of example llhave shown sixteen blocks, but it will be understood that any desiredmultiple of four may be used. If it be assumed for in-4 stance that theblocks at one side of a diametral line have lengths greater than theaverage and that the blocks at the other side of the line have lengthsless than the average, then it will be seen that after the diametraltransposition of alternate blocks the longer and shorter blocks will, inthe main, bs alternately arranged as shown in Fig. 4.' The operator hasno means of determining the-position' of the diametral dividin line -w'and no means of determining w ich is the side of maximum length andwhich the side of minimum length, but it is not necessary for him to doso. It'will be observed .that inasmuch as the alternate blocksthroughout the entire series are transposed, the `required alternatearrangement of longer and shorter blocks is secured ir- 'espective ofthe position of the dividing The blocks having been transferred asdescribed, the top lap is restored to position and the lapping operationis repeated. Ob-

viously the laps will at first engage only the longer blocks, thusreducing their lengths. The lapping operation is continued preferablyuntil the laps again'engage all of. the blocks. Obviously the blocks aremore nearly uniform in length than before but there may still be somevariation. Therefore alternate blocks are again transferred, as beforedescribed, and the blocks are again lapped. These operations arerepeated alternately in succession for a vnumber of times,

and the final result is that all of the blocks have the same length andhave their end surfaces flat and parallel.

The manner of moving or transferring the blocks may be varied,particularly in the ways set forth in my aforesaid application. It maybe also desirable to change the blocks by turning some of them through180 as indicated 1n- Fig. 5.

The blocks having been made with identical lengths and with planeparallel end surfaces, the lapping operation is then continued to reducethe lengths to the desired predetermined amount. If considerableadditional lapping is required to secure the desired uniform length. itmay be preferable to continue the transferring of the blocks* from timeto time to avoid possible variations. The blocks may be measured in anydesired way to ascertain when the predetermined lengths have beenreached. Use may be made of the method set forth in my aforesaidapplication, but this method constitutes no part of my present inventionand. need not be here described.

What I claim is: y

1. The method of reducing a number of similar blocks to produce parallelfiat end faces and identical lengths, which consists in placing theseveral blocks with one end face of each in engagement with a flatsurface plate, placing a flat lap in engagement with the opposite endfaces of the blocks, permitting'the lap to adjust itself as toparallelism with the surface plate in accordance with the lengths of theblocks, moving the lap with respect to the blocks to effect lapping,interchanging some of the blocks on the surface plate to symmetrically mwith the opposite end faces of the distribute variations in length, and.repeating the lapping operation.

" 2. The method of reducing a number of similar blocks to produceparallel flat end faces and identical lengths, which consists in placinthe several blocks with one end face of eac in wringing engagement witha Hat surface plate, placing a fiat lap in enagement with the oppositeend faces of g the blocks, permitting the lap to adjust itself as toparallelism with the surface plate in accordance with the lengths of theblocks, moving the lap with respect to the blocks to effect lapping,interchanging some of the T5 blocks on the surface plate tosymmetrically distribute variations 1n length, and repeating the lappingoperation.

3. The method of reducing a number of similar blocks to produce parallellat end faces and identical lengths, which. consists in placing theseveral blocks in a circular series with one end face of each inengagementl with a flat surface plate, placing a Hatv lap in engagementwith the opposite 25 end faces'of the blocks, permitting the lap Vtoadjust itself .as to parallelism with the surface plate in accordancewith the lengths of the blocks, moving the lap with respect to theblocks to effect lapping, interchang-y 3" ing some of the blocks on thesurface plate with those diametrically opposite to sym- 'm'etricallydistributeV variations in. length, and repeating the lapping operation.

4. The method of' reducing a numberI of similar blocks to produceparallel dat end faces and identical lengths, which consists in placingthe several locks with one 'end face of each in engagement with a iiatsur'- moving the lap with respect to the blocks in a circular path andsimultaneously rotatin it to effect lapping, interchan g some o theblocks on the surface p ate to symmetrically distribute variations `inlength,

rn and repeating the lapping operation.

5. The method of reducing a number of similar blocks to produce parallelfiat end faces and identical lengths, which consists in placing theseveral blocks with one 'end face of each in engagement with a flatsurface plate, placing a flat lap in engagement with the opposite endfaces of the blocks, permitting the lap to adjust itself as toparallelism with the surface plate in accordance with the lengths of theblocks, moving the lap with respect to the blocks to eiect lapping,reversing the blocks end for end and again placing them in engagementwith the surface plate, again placing the lap in engagement with theblocks, permitting'the lap to adjust itself as to -parallelism with thesurface plate in accordance with the lengths of the blocks, moving thelap with respect to the blocks to effect lapping, interchanging some ofthe blocks on the surface plate to symmetrically distribute variationsin length, and repeating the lapping operation.

6. The method of reducing a number of similar blocks toproduce parallelfiat end faces and identical lengths, which consists in placing theseveral blocks with one end v'face of each in engagement with a Hatsurface plate, placing a iiat lap in engagement with the opposite endfaces of the blocks, moving the lap with respect to the blocks to eiectlapping, interchanging some of the blocks on the surface plate tosymmetrically distribute variations in length, and repeating fthelapping operation.

7. The method of reducing a number of similar blocks to produce parallelatend faces and identical lengths, which consists in placing the severalblocks with one en d face of each in engagement with a Hat surfaceplate, placing a fiat lap in engagement with the opposite end faces ofthe blocks,

moving the lap with respect to the blocks to effect lapping, reversingthe blocks end for end' and again fplacing them in engagement with'thesur ace the lap in engagement with the ocks, 4movin the lap with respectto the blocks to e ect lapping, interchanging some of the blocks on thesurface plate to symmetrically `distribute variations in length, andrepeating the lapping o eration.

In testimony w ereof, I hereto aix my si ature.

gn Enom.'

plate, again placingl

